There is still considerable uncertainty about the accurate classification of human hematopoietic tumors, as well as great variability in prognosis and in response to treatment, not only among different tumors, but also within any one diagnostic category. More precise diagnosis and definition of the relationships between these tumors is therefore important, not only in terms of reaching a clearer understanding of their cellular orgins, but also in predicting prognosis, evaluating current treatment regimens, and developing more effective methods of therapy. The main purpose of this renewal application for this Program Projectr remains the same, namely to carry out a comprehensive clinical-laboratory investigation of all varieties of hematopoietic tumors, with emphasis on correlating the results of newer laboratory studies which have potential clinical relevance with conventional hematological and pathological diagnostic criteria, and with clinical data on staging, responsiveness to treatment, and survival. The investigations include determination of surface and biochemical markers and specific receptors, cytokinetic parameters of tumor cells and subpopulations, size distribution, clonogenic potential in short-term culture systems, response to mitogens, physiologic regulators and drugs, interactions with other cell types in culture, establishment of human tumor cell lines, correlation of specific cytogenetic abnormalities with cell type and prognosis, cytofluorometric measurements of DNA and RNA content and cell cycle distribution and preparation of monoclonal antibodies to specific cell types. The eventual goals are to develop an objective and scientific classification system for human hematopoietic tumors based on the origins and functional properties of the cells, to identify the critical prognostic factors at the time of diagnosis, and to develop more selective and effective treatment programs.